Directional antenna system



y 1951 J. J. ROOT DIRECTIONAL ANTENNA SYSTEM Filed Oct. 22, 1949Patented May 15, 1951 "UNI TED PATENT CE DIRECTION-AL ANTENNA SYSTEMJohn J .rRoot, New York, -N. Y. "Applicatiomoctober 22, 1949; 'SerialNo.-123;il22

6 Glaims.

This invention relates to high frequency antennasfor use intelevisionandfrequency modulation receivers.

In the art of television reception, as'presently known, it is almostessential to employ a direc tiveantenna which is furtherlof a size toresonate approximately within the frequency range of reception. When thetelevision receiver is in .a so-called fringearea, a term referring toareas "at ,a substantial distance from the televisionytransmitter, itissgenerally necessary to employ a, more or. less, elaborate antennahaving elements of adequate size: tOlGSOITlQJZBTatLfihI-B de- .:siredifrequencies. :When the rreceiver is closer xtothe televisionrstation,lthexa-ntenna maybe correspondingly.simplified:although it is rare. in

actual practicexthat oneimayibe dispensed with :entirely.

Theneed'for'a simple, smalltantenna for television receivers located;in1l arge cities-has been very great. A'major. reason is that thepopulation of such large cities ioften inhabit. apartment houses" wherethe use of;a great. number of individual, elaborate antennas isinconvenient, if not impossible. Furthermore, the provision :of asmaller, simplified antenna obviously ofiers con siderablemanufacturingand installation economies. Asa result of the above need, there havebeen developed antennas which .are disposed withinthe televisionreceivercabinet;but,:as far as I am aware, suchwantennas have been extremelyineificient. Inaaddition, it was often necessaryto, orient the antennain ordertoiniprove reception, and the physical orienting of the cabinetswas then necessary. It will belevident that this may be very impracticalsince the cabinet may berequired to. be so turned that the viewing tubeis :directed away from the spectators.

With the above in mind, It-have devised an antenna to be incorporatedinia television cabinet whichais of pronounced efficiencyand provides ausable signal within reasonable distances from the televisiontransmitter. The. instant antenna employs crossed dipoles,=as willhereinafter ap- ('CL- 25 0-v33-51) 2 i :so that-the: cabinetvjitselfneed :notvbe. moved :at -all. Orientation ofthexantennaiis:thenuaccomplishediby means: of;-a knobidisposedon .the;cabinet which rotates the condenser 1'otor -and*effectively orients theantenna.

'iTheantenna of,theinstantfinvention may also be constructed withoutitherappendix sabove referred to butwmay. utilize insteadz a matchingstub as will behereinafter made; clear.

The inventionwilkbe :further:understoodr'irom the following-3descriptionandv drawings in which -Fig. leis aperspective view Z'OfFiiYJEEIBViSiOIIreceiver cabinet equipped with the built-in antenna 1 of .the :instant Linvention.

Fig. 2 is arragmentarya viewtaken :su-lastantially U along- ;the lines;2- -2 of: Fig. :1.

Fig; 3 is a fragmentary plan :view lZOf'?:9/i terminal end of i one oftheantenna: dipoles.

Fig. 4 is a substantially:schematicillustration of 1 the-antennainstallation-- of a Fig. 1.

;Fig. '5 illustrates 'armodification .ofzxthe antenna dipoles-support.

The cabinet 0 illustrates -.a;conventiona1- televisioncreceiver "cabinet.but it will: be evident; that it maytassume manydiverse'forms. in-theterm shown; the antenna; .compriseadipole sections l l .and. I I formingone dipole and dipolesections- !2 and i3 forming "another 4(1113018. Thedipoles are maintained-in crossed relationship {so i that .they are.perpendicular in relation .-.to each other. For: convenience of handlingandinstallation; the .dipole. sectionsare-fastenedasby-stap1es t4 tominsulatingaboard 15. Board lfi maybetof cardboard or: any of thewell-known plastic :materials ...genera1l-y used forrinsulationpurposes. Board l5 may. be. fastened-ate ,the cabinet: ceiling by. meansof .nails or. screws! 6.

.In the form :shown, dipole sections bland #3 l are .bridged by an"elongated conductor. IT which may be -'integral=;-withthe dipolesections I-E! and l3. ,It...has been: found that such. bridging or short,circuiting increases the, impedance.- match between the, antenna andthe ,receiverinput and further increases. gain at the; low.,frequencies.

The dipole sections andbridging-conductor 1 ll may .take.,the,f0-rm..0fflat: metalpstrips-asillustrated. Theaterminal ends .T ;ofthedipolesections are. formed as illustrated in Fig. .3 by means tofnaslot 18 and hole [9, the sloteliltpermitting .theuterminal end-to bebent. downwardly as illustratedl in. Figs. -llandv2 so -as ,to providealug-to .Which..soldered connections may. be made. The hole is serves.its usual vfunctiontof permitting .the initial .introductionflofwireslfi and '2! ,;pre ,paratory .to.,solderin-g Ythem ..thereto.

No. 72,700, filed January 25, 1949, but it may further take the improvedform illustrated herein.

Wires 29, 2|, 22 and 23 are effectively respectively connected to wires25*, 26, 21 and 28 which are in turn connected to the lugs 29, 39,- 3Iand 32 of the condenser stator plates 33, 34, 35 and 36. Thus, eachcondenser stator plate represents one dipole section. Condenser 25 maybe mounted within the cabinet in any conventional manner, the condensershaft 31 extending therethrough so that an actuating knob 38 may beemployed to operate the condenser, as will be hereinafter described.

To the shaft 31 are'connected two rotor plates 39 and 49 havingcapacitative action with the stator plates. It will be recognizedthatrotation of the plates 39 and 49 will serve to select input voltagesfrom any particular diametrical position of the stator plates. 'In thisway, rotation of the rotor plates acts as quadrant selection in respectto the dipoles to which the stator plates are connected.

Lugs 4i and 42 are respectively connected to the g rotor plates 39 and49 so that wires 43 and 44 represent the output of the antenna and arecorrespondingly connected to the input of the television receiver.Terminals 45 and 46 represent such receiver input'terminals.

A particular'advantage is derived by connecting a metallic conductor 41to either one of the rotor plates or the terminal represented thereby.Thus, conductor strip 4'! is connected to terminal 46 and it is madefast to the backboard 48 of the television receiver as by staples l4.Because of the physical appearance of conductor strip 41, I havereferred to it as an appendix. Strip 41 is very useful in increasing thegain of the antenna, particularly for the low frequencies. Referring toFig. 4, I have further illustrated the provision of a lug 49 which isconnected to strip 41. It has been found that further'gain isaccomplished by clippingthe strip 41 to the conventional power line cordof the receiver at any convenient point. Lug 49 is therefore provided tofacilitate such clipping. It is believed that capacitative actionbetween strip 41 and the ground wire of the power line cord isresponsible for such increased gain.

In. Fig. 5, I have illustrated the same essential antenna structureexcept that the board l5 is replaced by a central insulating member 59,the dipole sections being stapled thereto and thereafter being loose orhanging. With this construction, the dipole sections are merely nailedor stapled directly to the cabinet ceiling.

The operation of the antenna system described will be apparent from theabove explanation. Briefly, the directional dipoles accommodate signalsreceived from an direction. The signals are then selected throughrotation of the variable condenser so as to effectively orient theantenna in space, although it is physically motionless. The conductor Iwhich connects the free end of one of the dipole sections to the freeend of an adjacent dipole section appears to exercise an in- 4 ductiveeffect so as to compensate for the short ness of the dipoles. Conductorstrip 41, which is connected to one of the rotor plates, may be of alength approximately equal to either of the dipoles but such length isnot critical.

The use of appendix conductor strip 4'! may be supplanted by aconventional matching stub connected between terminals 45 and 46. Suchmatching stubs are well known and are generally U- shaped. Connectionsto the receiver input may be made along respective points of the arms ofthe U, such points being selected pursuant to the impedance of thereceiver input to be matched. However, neither the appendix conductorstrip 41 nor a matching stub is essential to the operation of theantenna system and may therefore be eliminated in constructing asatisfactory antenna.

Details of construction of condenser 25 are not included nor claimedherein. However, the condenser may follow the form described in my priorapplication as aforesaid but may preferably take the form of a condenserwhich is the subject matter of a patent application being filedherewith.

Whereas I have referred to the action of the rotary condenser aseffectively rotating the dipoles, the condenser inherently embodiesother functions and advantages such as properly phasing the picked-upsignals although they may be arriving at the antenna out of phase Inaddition, it is believed that the condenser provides a tuning actionwhich increases gain.

What is claimed is:

1. A television antenna system comprising a pair of directional elementsdisposed so as to be efiectiv-e in substantially mutually perpendiculardirections, variable means for electrically combining the outputs ofsaid directional elements so as to effectively orient the pair ofdirectional elements, the end of one of said directional elements beingconnected to an adjacent end of the other directional element.

2.A television antenna systemcomprising a pair of dipoles crossed so asto be effective in substantially mutually perpendicular directions, theterminal ends of said dipoles being adjacent each other, variablecondenser means connected to said terminals for effectively rotatingsaid dipoles in space, an outer end of one of said dipoles opposite to aterminal end thereof being connected to an outer end of the otherdipole.

3. A television antenna system comprising a pair of dipoles crossed soas'to be effective in substantially mutually perpendicular directions,the terminal ends of said dipoles being adjacent each other, variablecondenser means connected to said terminals for effectively rotatingsaid dipoles in space, an outer end of one of said dipoles opposite to aterminal end thereof being connected to an outer end of the other dipoleand a conductor extending from said variable condenser means and being alengthapproximately equal to said dipoles.

4. A television antenna system comprising a pair of dipoles crossed soas to be effective in substantially mutually perpendicular directions, arigid support for maintaining said dipoles in crossed position, theterminal ends of said dipoles beingadjacent each other centrally of saidsupport, a condenser including four stator andtwo rotor plates, saidrotor plates being arcuate and jointly forming a circle while beinginsulated from each other, the terminal ends of each dipole beingconnected to diametrically opposite stator plates, said rotor platesbeing adapted to provide voltages by capacitive effect from said statorplates for connection to the input terminals of a television receiver,and an elongated conductor effectively connected to and extending fromone of said rotor plates, said-elongated conductor terminating in a freeend.

5. A television antenna system comprising a pair of dipoles in the formof electrical conductors and crossed so as to be effective insubstantially mutually perpendicular directions, said conductors beingflexible, supporting means for maintaining said conductors in saidcrossed relationship, the terminal ends of said. dipole conductors beingdisposed adjacent each other, an electrical conductor extending linearlyand connecting the outer end of one dipole conductor opposite itsterminal end to the outer end of the other dipole conductor, andvariable condenser means comprising four stationary condenser plates,each of said condenser plates being respectively connected to the fourterminal ends of the two dipole conductors, said variable condensermeans further including a pair of rotor plates for electrically rotatingthe directional characteristics of said crossed dipole conductors.

6. A television antenna system according to claim 5 and including aconductor electrically connected to one of said rotor plates, saidlastnamed conductor being of a length approximately that of said dipoleconductors.

JOHN J ROOT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,188,649 Carter Jan. 30, 1940 202,190,816 Wheeler Feb. 20, 1940

